CONICET | Buscador de Institutos y Recursos Humanos

Most industrial metallic products are produced by processes such as rolling, extrusion or drawing, involving large plastic deformation, unevenly distributed across the thickness of the piece. As a result, the crystallographic texture of the finished piece changes from point to point, presenting clear differences between the core, and inner and outer surfaces of the piece. These variations are relevant in applications where texture plays an important role in the material performance. Here, we describe a methodology to quantitatively characterize such texture distribution by performing neutron diffraction experiments in a TOF neutron strain scanner, where the gauge volume is accurately defined by the use of radial collimators. The description of a material texture is expressed in terms of the orientation distribution function (ODF) of the crystallites composing the sample, which can be readily defined from a number of experimental incomplete pole figures. To perform such task with a neutron strains scanner, we have developed NyRTex, a freely available Matlab library based on the texture toolbox MTEX. Essentially, the code performs the following tasks: (i) it splits the relatively large solid angle (typically 30x30 degrees) of detection banks in neutron strain scanners into smaller groups, (ii) it performs robust multi-peak least squares fitting of the diffraction data, (iii) it creates experimental pole figures from the Euler angles of the explored sample orientations and refined peak areas, (iv) it computes the ODF from the experimental pole figures. We present demonstration experiments on an archaeological bronze and a rolled aluminum plate performed on the ENGIN-X beamline at ISIS, UK; together with a spatially resolved texture analysis of Zr2.5%Nb pressure tubes from CANDU nuclear power plants.

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